Monday, November 05, 2012

Does Calcium Inhibit Iron Absorption?

Does calcium inhibit iron absorption? According to the study below, yes, but the effect is temporary and adaptation occurs, resulting in no appreciable impact on iron status.

Calcium And Iron Absorption - Mechanisms And Public Health Relevance, International Journal For Vitamin and Nutrition Research, October 2010

Researchers at the University of California, Davis, set up an intestinal cell culture model and assessed calcium (Ca) and iron (Fe) interaction and transport. From the abstract:

"Studies on human subjects have shown that calcium (Ca) can inhibit iron (Fe) absorption, regardless of whether it is given as Ca salts or in dairy products. This has caused concern as increased Ca intake commonly is recommended for children and women, the same populations that are at risk of Fe deficiency.

However, a thorough review of studies on humans in which Ca intake was substantially increased for long periods shows no changes in hematological measures or indicators of iron status. Thus, the inhibitory effect may be of short duration and there also may be compensatory mechanisms.
...
[We found] the effect of Ca on Fe absorption may be of short duration and adaptation may occur with time. This may explain why studies on long-term Ca supplementation of different groups fail to show any adverse effects on Fe status."

Interesting study. Even though Caco-2 cells are not perfect models of intestinal nutrient absorptions, there are humans trials that support the idea that calcium doesn't inhibit iron absorption when possible adaptation is allowed for: